MacBook Pro 17" early 2011 raid SSD's issue.

[pastarojna]

Hello,
Recently I decided to raid both of my SSD's on my MacBook Pro 17" early 2011.
Both SSD's are :Samsung SSD 840 PRO Series with 256 GB each. (Please see attached )
Anyhow i tried to raid both hard drives using Raid 0 , to maximize writing and reading speeds.
After running Blackmagic Disk Speed Test, the writing and reading speeds were vert LOW. (please see attachment).
I looked into this issue very shortly, basically the "CD tray can not send data at the same rate as the dedicated hard drive tray. I think it is this speed here (also see attached):

Samsung SSD 840 PRO Series-1:
Product: 6 Series Chipset
Link Speed: 6 Gigabit
Negotiated Link Speed: 6 Gigabit


Samsung SSD 840 PRO Series-2:
Product: 6 Series Chipset
Link Speed: 6 Gigabit
Negotiated Link Speed: 6 Gigabit


So, both SSD's are running the same at 6 Gigabit.
I am not sure what is the issue here, can some one please enplane it to me.

And i guess , another question.
If this is the issue of SATA speeds, should I just go back to 2 SSD's running a part?

Thank you